Telephone system



v E -EFT:

gra-20,1926. v 1,581,244

' S. SUEKOFF TELEPHONE SYSTEM Filed Sept. 10, IQLQ 3 Sheets-Sheet 5Wamay Patented Apr. 20, 1926. V

UNITED STATES SAMUEL SUEKOFF, OF CHICAGO, ILLINOIS,

PATE T F E-r ASSIGNOR TO KELLOGG SWITCHBOARD AND- SUPPLY COMPANY, OFCHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

' TELEPHONE SYSTEM.

Application filed September 10, 1919. s erial No. 322,780.

To all whom it mayconaem:

Be it known that I, SAMUEL SUEKOFF, a citizen of the United States ofAmerica,

residing at Chicago, in the county of Cook and State of Illinois, haveinvented certain new and useful Improvements in Telephone Systems, ofwhich the following is a specification. Y

My invention relates to telephone systems such systems. I

In a multi-exchange system, the different exchanges that form thecomplete system are generally of different size and capacity. Forexample, some of the exchanges may be of the 100,000 line'type; part maybe of the 10,000 line typeand part may be of the 1,000 line type.

In the 100,000 line type of exchange, first,

second and third selectors are provided,

while in the 10,000 line type only first and second selectors areprovided, and in the 1,000 line type only first selectors need beprovided. Of course, it is necessary to furnish connector switches, andnon-numerical switches with these different types of I systems.

In the 100,000 linetype of system,the subscribers numbers must contalnfive figures. In the 10,000 line type the subscribers numbers mustcontain at least four figures, and in the 1,000 line type thesubscribers figures must contain at least three figures. It has beenfound desirable, and the reason is thought to be apparent, to have allthe subscribers numbers in a system contain the same number of figuresor digits.

Heretofore it has been necessary to insert extra selector switches, forwhich there was no use, in the 1,000 and 10,000 line type exchanges, sothat all the subscribers numbers in the complete system would have thesame number of digits, thus causing a great and needless expense andoutlay in selector switches that were really not needed in the system tocomplete the calls.

It is the object of my invention to overcome this objectionable feature,as well as many other objectionable features.

A feature of my system is the provision of a selector switch which isadapted to ab- 5 sorb or render useless'one or more digits of a callednumber, thereby taking the place of several selector switches used inthe old type of trunking systems.

' I so arrange my selector switch that when in a 5 digit system, theselector switch will absorb or render ineffective one digit orthen're'spond to the next digit or series of impulses of the callednumber. my selector, in a smaller type of exchange, is arranged torender ineffective two series or more of impulses of the called number.

In the accompanying drawings I have omitted all unnecessary andwell-known ap paratus, showing only the necessary apparatus forobtaining a full and clear understanding of my invention.

a call goes into a 10,000 line type exchange Likewise,

series of impulses of the called number and The above features, as wellas others, will be more particularly pointed out in the ensuingspecification and appended claims.

For a more complete understanding of my invention reference may be hadto the accompanying drawing in which Fig. 1 is a skeleton circuitdiagram illushating the application of my invention to a multi-otficesystem; and

Fig. 2, which comprises parts 1 and 2, illustrates diagrammatically thearrangement embodying my improved circuit arrangement. v

Referring now particularly to Fig. 1, I here illustratediagrammaticallya trunking arrangement between an exchange X and an exchange Y. Thesubstation A terminates in an individual line switch B at the exchangeX, whioh'switch may be of any suitable type, as the switch illustratedand described in a copending application of Harry H. Ide, filed July 29,1918, Serial No. 247,122. Upon the initiation of a call at thesubstation A, switch B selects an idle first selector switch C.- Theexchange X, as illustrated, is of the 100,000 line type, and theexchange Y is of the 10,000 line type. "With this size and type ofsystem it will be necessary'to have'5 digit numbers. Should thesubscriber at'the substation A wish to converse with the substation D inhis own exchange, a series of five groups of impulses will betransmitted to 3 actuate the different switches. The first set ofimpulses will actuate'the first selector C to select an idle secondselector E in the exchange X, and the second set of impulses willactuate the second selector E to select an idle third selector F. Thethird set of impulses will actuate the third selector F to select anidle connector switch G, which connector switch G contains the contactsof the called line D.

The last two sets of impulses actuate the connector G to engage thecontacts of the wanted line, as is well understood. Now should thesubscriber at the substation A wish to converse with a subscriber at thesubstation H which terminates in the exchange Y, the subscriber at thesubstation A in initiating a call actuates his line switch B to selectan idle first selector G in the exchange X, and then actuates hisimpulse device to send live sets of impulses to select the contacts ofthe wanted substation H at the exchange Y. The first set of impulsesactuates the first selector C at the exchange Y to select an idleincoming second selector J at the exchange Y. The second selector J atthe exchange Y is provided with the digit absorbing feature of myinvention, and the next set of impulses is absorbed and does not affectthe switch mechanism, as will be more fully hereinafter described. Thenext set of impulses, which is the third set, now actuates the secondselector J to select an idle connector L which connector L contains thecontacts of the wanted substation H. The last two sets of impulsesactuate the connector L to select the contacts of the wanted substationH. It may thus be seen that a system as above outlined with a digitabsorber selector installed in an outlying exchange eliminates the useof a third selector, this allowing a imiform numbering system inaddition to eliminating the third selectors.

It is, of course, understood that my invention is applicable to a systemor systems of any size and that the switches may all be located in oneexchange or any number of exchanges, the main feature being to keep thesubscribers numbers uniform, that is, to have the same number of digitsin each figure. In case it is desirable to absorb or render useless twodigits, two of my digit reducing selectors will be provided. It isfurther to be understood that a repeater may be provided between thefirst selector C and the second selector J in the distant exchange, ifit is found desirable, of the general type illustrated and described inUnited States Letters Patent to Alfred H. Dyson No. 1,148,665, grantedAugust 3, 1915.

The selectors and connectors shown may be of any approved type.

Referring now to Fig. 2, which comprises parts land 2, and moreparticularly to part 1, 1 illustrate a well known type of substationincluding the usual substation apparatus, and in addition I show acalling device CD. The substation A terminates at the exchange, which wewill assume is the exchange X of Fig. 1, in an individual line switch B.The line switch B is provided with a rotary shaft and carries a pri vatetest wiper 2 and a pair of line wipers 3 and 4-. A line relay LR isprovided which is energized over the subscribers line conductors inseries. A cut-off relay CO is also provided for disconnecting thesubscribers line circuit from the line relay LR- and for connecting theswitch wipers to the subscribers line circuit. A motor magnet MM isprovided for stepping the switch wipers 2, 3 and 4 step-by-step over thebank conacts 5, 6 and 7. An off-normal contact ON is provided whichmoves to its alternate position upon the first step of the wipers offnormal. The wipers 2, 3 and l are spring restored, and are adapted to bereleased to normal when the cutoff relay CO de-energizes. In Fig. 2,part 1, I do not show the first selector G associated with the exchangeX as the operation of the selector switch is well known and for the sakeof simplicity I have omitted it and for a detailed description of thesame reference may be had to U. S. Patent No. 1,402,936 granted January10, 1922, to Harry H. Ide. The selector switch J is a combined secondand digit absorbing selector and is provided with a private wiper 8 andline wipers 9 and 10, which connect with an idle connector. A primaryrelay PR and a primary magnet PM are provided, which magnet PM steps thewipers 8, 9 and 10 in a primary direction to a pre-determined group ofcontacts. A secondary relay SR and a secondary magnet SM are provided,which magnet SM steps the wipers 8, 9 and 10 in a secondary directionover the contacts 11, 12 and 13 to seek an idle set of contacts in theselected group. A combined line and interrupter relay IR, which whende-energized and energized, due to the interruptions of current at thecalling substation, brings about the deenergization and energization ofthe primary magnet PM to step the wipers 8, 9 and 10 in a primarydirection. Digit absorbing or reducing relays DR and DR are provided forpurposes as will be more fully hereinafter described. A switching relaySW is also provided, and energizes when an idle connector is encounteredto ex tend the calling'line to the said idle connector. magnet RE areprovided, which magnet RE upon energization releases the switch J tonormal when disconnection is desired. The primary off normal contactsPON are provided, which assume their alternate position upon the firststep of the wipers 8, 9 and 10 off-normal, and are again restored uponthe restoration of the switch J to normal. Overrun contacts OR areprovided, which assume their alternate position upon the eleventhsecondary step of the wipers 8, 9 and 10,

A release relay RR and release that is, whenall of the-contacts of theselected group are busy, in which event the busy back apparatus BB isconnected to transmit a busy signal back to the calling subscriber. v

The connector switch L illustrated in Fig. 2, part 2, comprisestheiu'ipulse relay IR, a private relay PV, a secondary relay SR and aprimary magnet PM. A rotary magnet RM is also provided, which. isenergized by the last set of impulses to step the wipers lei, 15-and 16of the connector L in a rotary direction over contacts 17, 18 and 19 toselect the. contacts of the wanted line. A busy relay BB is associatedwith the connector and connects the busy back appara tus BB to thecalling line in case the called line is busy. A ringingrelay RI is intermittently energized and. deenergized by the interrupter I toconnectthe'rlnglng generator G to the called-torl1ne to actuate the call signalthereat. A ringing control relay RCR' is energized when the subscriberat the called substationv answers to disconnect the ringing generator Gfrom the called' A release relay RR and a release line. magnet-RE areassociated withthe connector,'the magnet R I. being energized upon thede-energization of relay RR to release the switch mechanism. Areversing'relay RV is also shown for the usual battery reversingpurposes, as is wellunder- Off-normal contactsON are prostood. vided andassume their alternate position upon the first step of the wipers 14, 15and 16 off normal. 21,22 and 23 are stepped'to their difierent positionsby the restorations of the relay PV. I I

A substation H is shown at the right of Fig. 2, part 2, and is similarto that of A and is connected at the exchange with its associated lineswitch B, similar to B.

Having described in general the apparatus associated with my invention,the op eration of the system will-now be described more in detail. Asbefore mentioned, it is to be'assumed that a first selector is to beprovided and inserted between the line switch B and the digit'reducingselector J.

Assuming nowthat a call is to be traced from'the. calling substationA-in the ex change X to a called substation Hat the eX- tion switch hookto ground at normal-contact 27 of cut-off relay CO. The line relay LRupon energizing establishes an energizlng circuit for motor magnet MMtraced The side switch wipers 20,

from battery through the winding of magnet MM, itsnorm'al contact 28 toground at alternate contact 29 of relay LR, and the opening of normalcontact 24 of motor magnet MM opens the energizing circuit of linerelay'LR, and magnet MM steps the wipers 2, 3 and 4 of the line switch Binto engagement with the first set of contacts 5, 6 and7, which lead toa first selector (not shown) of the type previously referred to. Uponthe first step of the wipers off normal, the oil normal contacts ONassumetheir alternate position and the contacts 30 and 31 are also movedto their alternate position. The open ing of alternate contact 29 ofline relay LR bring'sabout the de-energization of the magnet MMand'should the private wiper 2 of the line switch B engage a busyprivate contact 5 upon this first step, a substitute circuit for theline relay LR is established, traced from battery, through the windingof relay LR, normal contact 24 of magnet MM, alternate contact 25 ofoff-normal contacts ON and alternate contact 31 to ground to the busycontact engaged by the private wiper 2. The closure of alternate contact29 of relay LR again establishes a circuit for the magnet MM aspreviously described,

causing the switch wipers'2, 3 and 4 to take ,v another step and; engagethe second set of",

contacts 5, 6 and 7. If'the next private contact "5 is busy, motormagnet MM and line relay LR are again energized andde-energized to stepthe wipers 2, 3 and 4 step by step until an idle private contact 5 isencountered. When a contact 5 leading to an idle first selector has beenseized, the line relay de-energizes, bringing about the deenergizationofthe magnet MIM. The closing of normal contact 32 of relay LR establishesan energizing circuit for the cut-off relay CO, traced frombattery'through the winding of fsaid cut-ofi relay CO conductor 33,normal contact 32 to ground at alternate contact 30. The energization'ofcut otf relay CO brings about the restoration of the contacts '30 and 31to their normal position,

opening'the initial energizing circuit of the cut-oft relay CO, but asthe cut-off relay CO 1s slow to release a substitute'circuit isestablished'for the said relay CO before it has time to de-energize andits contacts restore to normal, from ground which is transmitted backfrom the idle first selector which has been seized.

I have not shown in detail a local first selector, as a selector of anywell-known type maybe employed as the selector illustrated in Patent No.1,344,195, issuedto G, A. Yanochowski, J une'22, 1920. j 1

Assuming that thenumber of the called subscrlber at substation H in theexchange Y is 23456, the subscriber at thefcalling substation A in theexchange actuates his c'allin'g devicefCD to send two'impulses ofcurrent, which impulses represent the first digit of the called numberof the called subscriber at substation H. The impulses of currentactuate means which bring about the movement of the first selectorswitch wipers 70, 71 and 72 (see Fig. 1), in a primary di rection toselect a group 01' trunks, which lead to the exchange in which thecalled substation II terminates. The selector switch is then stepped ina secondary direction over the contacts 7 3, 7 4, and 75 to select anidle set of: contacts leading to an idle incoming second selector in theexchange in which the called substation terminates. The wipers 70, 71and 72 engage contacts 73, 74 and 75, which lead to an idle incomingsecond selector J at the exchange, which selector is provided with adigit reducing means and the engagement of wipers with said contactsbrings about the energization of the combined line and impulse relay IR,over a circuit traced from battery through the lower winding 34 of theimpulse relay IR (switch J, Fig. 2, part1), conductor 35, normal contact36 of the switching relay SW', contact 74, wiper 71, contact 6, wiper 3,alternate contact 27 of the cut-oii' relay CO, through the substation A,back through alternate contact 26 of relay CO, wiper 4, contact 7, wiper72, contact 75, normal contact 37 of the switching relay SW, conductor38, through the upper winding 39 of relay IR, conductor 40 to ground atthe make-beforebreak contact 41 of the overrun contacts OR. The relay IRupon energizing closes its alternate contact 42, establishing anenergizing circuit for the release relay RR, traced from battery,through the winding of relay RR, conductor-43 to ground at alternatecontact 42 ofrelay IR. The calling subscriber at the substation A nowactuates his calling device CD to send three impulses of currentwhich-bring about three de-energizations and energizations of theimpulse relay IR. Upon the first de-energization of relay IR, theclosing of normal contact 42 of relay IR establishes an energizingcircuit for the digit absorbing relay DR over a circuit traced frombattery, through the winding of relay DR, conductor 50, normal contact51 of the digit absorbing relay DR, conductor 52, make-before-breakcontact 53 of relay DR, conductor 54, alternate contact 55 of relay RR,conductor 56, normal contact 57 of relay Sl/V and conductor 58 to groundat normal contact 42 of relay IR. The closing of alternate contact 59ofrelay DR closes an energizing circuit for the digit absorbing relay DRtraced from battery through the winding of the relay DR, itsmake-before-break contact 60, conductor 161, alternate contact 59 ofrelay DR, conductor 62 to ground at alternate contact 44 of relay RR.Relay DR now closes a locking circuit for itself traced front battery,through the winding of the relay DR, its alternate contact 63, conductor62 to ground at alternate contact 44 of relay RR. The opening ofalternate contact 51 of relay DR opens the initial energizing circuit ofrelay DR, but a substitute circuit is established for relay DR, tracedfrom battery, through the winding of the said relay DR, its alternatecontact 64, conductor 54, alternate contact 55, conductor 56, alternatecontact 57, and conductor 58 to ground at normalcontact 42 of relay IR,which circuit is established upon each de-energization of the relay IR.The relay IR is de-energized and energized three times, due to the threeimpulses of current, but relays DR and RR remain energized during therapid interruptions of the impulse relay IR, due to theirslow-to-release construction, and thus the second set of impulses whichconstitute the second digit of the called number of the calledsubscriber at substation H is absorbed with no movement of the switchmechanism as make-before-break contact 53 is open, preventing theimpulses from reaching primary magnet PM. After the last impulse ofcurrent, relay IR is again held in an energized position and contact 42assumes its alternate position and the digit absorbing relay DR restoresto normal. The calling subscriber at substation A now actuates hiscalling device to send four impulses of current, which bring about fourde-energizations and energizations of relay IR. Upon the firstde-energization of relay IR, its normal contact 42 is closed, thusestablishing a series energizing circuit for the primary relay PR andthe primary magnet PM, traced from battery, through the winding of themagnet PM, conductor76,through the winding of the primary relay PR, conductor 77, the alternate contact 51,conductor 52, make-before-breakcontact 53 of relay DR, conductor 54, alternate contact 55, con ductor56, normal contact 57 and conductor 58 to ground at normal contact 42 ofrelay IR. The contact 42 of relay IR is'closed and opened four times,due to the four impulses of current causing four energizations andde-energizations of the magnet PM, the said magnet PM stepping wipers 8,9 and 10 in a primary direction to the fourth group of contacts leadingto the four-hundred group of connectors.

The primary relay PR is held energized during the rapid interruptions ofrelay IR, due to its slow-to-release construction. Primary relay PR uponenergization closes its alternate contact 7 8 establishing an energizingcircuit for the secondary relay SR, the circuit beingtraced' frombattery through the winding of relay SR, conductor 79, al ternatecontact 80 of primary off-normal contacts PON, said primary ofi-normalcontacts having assumed their alternate position upon the first step ofthe'switch wipers oft-normal,-conductor 81, alternate contact 78,conductors 82;. and 49 toground at alternate contact 44 of relay RR. Theclosing of alternate contact 84 of relay closes normal contact 86 ofsecondary magnet SM.

conductors 83and49to ground at alternate contact 44 of relay RR. Afterthe last impulse of current, relay 1R- remains energized and primaryrelay PR- restores. The closing of normal contact 7 8 establishes an energizing circuit for the secondary magnet SM, the circuit being tracedfrom battery, through the winding of magnet SM, alternate contact 87 ofsecondary relay SR, conductor 88,:uormal contact 78, conductors 82, 83and 49'to ground at alternate contact 44 of relay RR. The secondarymagnet SM upon energization steps the wipers 8, 9 and 10 into engagementwith the first set of contacts '11, 12 and 18 and the opening of normalcontact 86 of secondary magnet SM opens the locking circuit of secondaryrelay SR, which restores and should the first private contact 11 engagedby the private wiper 8 be busy, a ground potential will be found bythewiper 8, and a circuit is established for the secondary relay SR, tracedfrom ground at the busy contact 11, through wiper 8, conductor 90,normal contact 91 of switching relay SW, conductors 92 and 93,

normal contact 94 of secondary magnet SM, conductor 81, alternatecontact: 80 of primary OH-normal contacts PON, conductor 7 9 andthroughthe winding of secondary relay SE to, battery. The secondaryrelay SR upon. energization closes its alternate contact 87,establishing a circuit for the secondary magnet SM over a pathaspreviously described. The secondary magnet SM uponenergization stepsthe wipers 8, 9 and 10 into engagement-with the second set of contacts11, l2 and 18, and magnet SM energizing opens the circuit for thesecondary relay SR at 94 and the secondary relay SR restoring opens thecircuit for the secondary magnet SM at contact.-87-.f If the secondcontact 11 is busy, secondary relay SR is again energized, bringingabout the energizationof magnet SM, and this see-saw action of thesecondary relay SR- and second-' ary magnet SM continues until an idlecontact 11 1S engaged, which is free from ground.

The circuit of relay SR is now maintained opened, thereby preventingfurther energizations of the secondary magnet SM.

An idle set of contacts 11, 12 and 13 having been engaged by the wipers8, 9 and 10 of the second selector, an energizing circuit for theswitching relay SW is established,

tracedv from battery, through the secondary relay SR,econductor -7 9,alternate contact 80 of primary ofli-normal contacts PON, normal contact94 of secondary magnet SM, conductor 93, through the Winding of theswitching relay SW, conductor 101, normal I contact 102 ofoverruncontacts OR, conductors 83 and 49 to ground at alternate contact '44 ofrelease relay HR. The switching relay SV is of comparatively highresistance, and the secondary relay SR being a relay of low resistance,the said relay SR fails-to energize. The opening of normal contacts 80and 37 of switching relay SW' opens the energizin circuit of theinterrupter relay IR, the may IR restoring to normal; The opening of itsalternate contact 42 interruptsthe circuit of the release relay RR.

The releaserelay RR, upon restoration opens 1t-s alternate contact 44 toopen the locking circuitforthe digit absorbing relay DR. The openingofalternate contact 44 of relay RR also opens the initial energizingcircuit of the switching relay SW, but the relay RR being slow torelease, the circuit of the switching relay SW is held momentarilyclosed until a substitute energizing circuit for the switching relay SWis established, as will presently be described. The second selectorhaving seized the idle connector L, the energizing circuit for thelineand'inter rupter relay IR is established, tracedfrom battery, throughthe upper winding of the relay IR, normal contact 100 of reversingrelayRV, contact 12, wiper 9 to the calling substation, throughthefsubstation, back to wiper 10 c0ntact 13, alternate contact'104 ofreversing relay RV, and through the lower' winding ioflrelay IR toground. Relay IR upon energization closes its alternate contact 105,establishing an energizin circuit for the release relay RR, traced Frombattery, through the winding of the relay RR, to ground at alternatecontact 105 of relay IR, The'closing of alternate contact 106 of relayRR closes a substitute'energizing circuit for the switching relay SW,traced from ground, through alternate contact 106, conductor 107,contact 11, wiper 8, conductor 90, alternate contact 91 of the switchingrelay SW', conductor 108,-conductor 83, normal contact 102 of overruncontacts OR, through the winding of the switching relay S"W,conductor:93'110111131 contact 94 of the secondary magnet SM, alternate contactof-primary ott-normal contact. PON, conductor --7 9, and throughtheWinding of the secinterrupter relay IR five times. On the firstde-energization of relay IR, an en ergizing circuit for secondary relaySR is established, traced "from ground at normal contact 105 of relayIR, through alternate contact 109 of relay RR, through the winding ofthe secondary relay SR, conductor 110, the winding of the primary magnetPM and through the side switch wiper 21 to battery. The relays RR and SRbeing slow acting do not de-energize in response to the rapidinterruptions of the relay IR, but the primary magnet PM being quickacting is responsive to the said impulses and steps wipers 14, 15 and 16to the fourth level of the switch contacts. The secondary relay SRremains energized while the impulses are being sent. The closure ofalternate contact 111 of relay SR establishes an energizing circuit forthe private relay PV, traced from battery, through the winding of therelay PV, conductor 112 to ground at alternate contact 111 of secondaryrelay SR. After the last impulse, the private relay PV de-energizes,having its circuit opened at alternate contact 111 of relay SR. The saidrelay PV de-energizing brings about the stepping of the side switchwipers 20, 21, 22 and 23 to their second position to engage contacts113, 11 i, 115 and 116. The side switch wiper 21 engaging contact 11 1now places the secondary magnet RM in series circuit with the relay SR.

The subscriber at the substation A next actuates his calling device CDto send six impulses, said impulses energizing and deenergizing theinterrupter relay IR six times. Upon each de-energization of relay IR,relay SR and secondary magnet RM are connected in series, the circuitbeing traced from battery, through the side switch wiper 21, contact 111, through the winding of secondary magnet RM, conductor 117, normalcontact 118 of the busy relay BR, conductor 119, through the winding ofsecondary relay SR, alternate contact 109 of release relay RR to groundat normal contact 105 of interrupter relay IR. The secondary magnet SMbeing a quick-acting relay is responsive to the quick interruptions ofrelay IR and steps the wipers 1 1, 15 and 16 to the sixth set ofcontacts of the fifth level, which are the contacts of the wanted line.The off-normal contacts ON assume their alternate position upon thefirst step of the switch wipers oil normal. The relay PV again restores,having its circuit interrupter at contact 111 of the relay SR. Thede-ener ization of the said relay PV steps the sid e switch wipers 20,21, 22, and 23 into their third position, engaging contacts 120, 121,122 and 123. The wiper 21 engaging contact 121 closes an energizingcircuit for the ringing relay RI traced from battery through the sideswitch wiper 21,

contact 121, conductor 124, normal contact 125 of ringing control relayRCR, conductor 126, through the winding of the ringing relay RI, throughthe interrupter I to ground. The relay RI is energized and decnergizedby the interrupter I to alternately connect and disconnect the ringinggenerator G at alternate contacts 127 and 128 oi the relay RI tointermittently ring the call bell of the called-for substation H. lVhenthe party at substation I-I removes his receiver from the switch hook inresponse to the call, the reversing relay RV operates, the circuit beingtraced from battery, through the lower winding of relay RV, normalcontact 129 of relay PV, normal contact 128 of relay RI, wiper 16,contact 19, through the now closed contacts of the substation switchhook, back through contact 18, wiper 15, normal contact 127 of relay RI,normal contact 130 of relay PV, to ground through the upper winding ofthe reversing relay RV. The operation of the reversing relay RV reversesthe original battery flow through the calling substation A. and thereversal of this battery current may be used for various purposes, as iswell understood in the art. The operation of the reversing relay RV alsocloses the energizing circuit of the ringing control relay RCR, tracedfrom battery, through the winding of the relay RCR, conductor 131,alternate contact 132 of relay RV, conductor 133, and wiper 20 to groundat the engaged contact 120. The energization of relay RCR opens thecircuit of the ringing relay RI at its contact 125; the ringing relay RIremains tie-energized, preventing further application of ringing currentto the called subscribers line. Relay RCR closes a locking circuit foritself traced from battery, through the winding of the said relay RCR,its alternate contact 134, over conduci'or 133, through wiper 20 toground at contact 120, the said relay remaining locked up to preventringing current being connected to the called line when conversation isgoing on. The conversational circuit may be traced over the heavilymarked conductors, the said conductors having the condensers K and Kinterposed.

hen conversation has been completed, the subscribers at the substationsA and H restore their respective receivers andthe restoration of theswitch hook at the called substation I-I brings about thede-en'ergization of reversing relay RV again reversing the battery flow.The replacing of the receiver at the calling substation A opens theenergizing circuit of impulse relay IR of connector L and therestoration of relay IR opens the circuit of release relay RR at contact105. Release relay RR restoring to normal closes an energizing circuitfor the release magnet RE traced frombattery,

. .connector'switch L. The opening ofalter.

nate contact 106 of relay RR removes;

ground from conductor 107 and private con tact 11, opening the circuitof switchingrelay SW, and the. said relay restoring closes itsnormalcontact .57 closing a circuit for the release magnet RE traced'from battery through the winding of relay RE, conductor 172, alternatecontact 173 of primary ofi's normal contacts PON, conductor 174k, normalcontact 53 of relay RR, conductor 56,

normal contact 5'7 of. relay SW, conductor 1 g the spirit and scope ofthe appendedclaims.

58 to ground at normal contact 42 ofrelay IR. Magnet RE uponenergization restores the switch-J. The restoration of the firstselector C at; exchange X removes ground from switch B. The'apparatusused in establishing .the connectionis now at normal and 1s availablefor establishing other connections.

Assuming that the subscriber at the substationA-lms operated hiscalling-device CD to send the last set of impulses, which are six innumber, and that the called substation L is busy, a ground will be foundconnected to the engaged contact 17. The engaged ground closes anenergizing circuit for the busy relay BR, traced from the battery, through the winding of the private relay PV, conductor 112,make-before-break contact 136 .of relay SR, through the windingof therelayiBR, make-betore-break contact 137ofrelay BR, conductor 138,contact 113, side switch wiper 20 and conductor 135 to ground throughwiperld of the busy engagedcontact 17. The last set of impulses, six innumber, having been sent, and the busy line encountered by the connectorwip ers. it is seen that the private relay PV remains energized. Theoperation of the relay ,BR closes its alternate contact 140,establishing a. locking circuit for itself, traced from battery, throughthe Winding of relay PV conductor 112', contact 136, through the windingof relay 'BR, alternate contact-14b0, V

conductor 1&4, contact .116,side switch wiper,-

23, which is in its second position, and back to the calling substation,this busy signal notifying the calling subscriber that tlre called lineis busy. The subscriber at'substation A receiving the busy signalreplaces,

his receiver and brings about the restoration of the apparatus, asbefore described- A connection established between subscribers inexchange X is established by use of said switches inert during thetransmissending of the local ffirst, second, third selectors andconnector switches in exchange If itis founddesirable, the extrarelaysmay be duplicated in selector J, so that any desired numbervotdigits may be absorbed.

The selector switch J may also be used as a third or' fourth selector,if found desirable,

as is readily understood from the previous I-Iaving described myinvention, what I claim as new and desire to secure byjUnited.StjatesLetters Patent, isz

1. A. telephone system including a subscribers impulse-sending devicefor transm'itting' seriesof impulses, and automatic side-switchlessswitches responsive to, said device, one of said'automatic switchesbeing provided with means for rendering inefi ec tive one of said seriesof impulses of any number of impulses to mamtaln sa1d one sion ofsaidoneof said series of impulses, and for operatively responding to anotherof said series of impulses to-etfect the operation.

of said one of said automatic switches.

, 2A telephone systemincluding a pair of subscriberlstelephone lines, animpulsedevice for one of said 'lines for transmitting series ofimpulses, and

automatic progressively movablej sidef switchless 'swltches responsiveto said series;

ofimpulses for extending connection from oneof said, lines to the other,one of said automatic switches being provided with means for renderingineffective one of said series of impulses regardless of thehumber-of'impulses of said one series'to render said oneiot saidautomatic s'witchesi'nert duringthe' transmission of said one of saidseries-,ofimpulses v2 3. A telephone system including .a callingsubscribers line provided with an impulsesending device for transmittingserie'sof impulses, a called subscribers, line, an automatic'selectorswitch r'esponsiveto a series of impulses for extending a connectionfrom said calling subscribers ,line towards the called subscrlbefis hne,and a second autojmatic side switchless selector switch, pro-.'

of impulses to render said second automatic switch operative to extendsaid connection from said first mentioned selector switch towards thecalled subscribers line.

4. A telephone system including a central exchange, a callingsubscribers line terminating thereat, a called subscribers lineterminating in a second exchange, another called subscribers lineterminating in a third exchange, an automatic calling impulse-sendingdevice at the calling substation for transmitting series of impulses,selector switches each responsive to a series of impulses for extendingconnection from said calling subscribers line to said first calledsubscribers line, and other side-switchless selector switches forextending connection from said calling subscribers line to said secondcalled subscribers line, one of said latter selector switches beingprovided with means including a pair of slow-acting relays cooperativelyassociated for renderlng ineffective one of said series of impulsesregardless of the number of impulses in said one series to render saidone of said latter selector switches inert during the transmission ofsaid one series.

5. A telephone system including a central exchange, a callingsubscribers line terminating thereat, a called subscribers lineterminating in a second exchange, another called subscribers lineterminating in a third exchange, an automatic impulse-sending device atthe calling substation for transmitting series of impulses, selectorswitches each responsive to a series of impulses for extendingconnection from said calling subscribers line to said first calledsubscribers line, other side-switchless selector switches for extendingconnection from said calling subscribersline to said second calledsubscribers line, one of said latter selector switches havingelectromagnetic means for rendering one of said series of impulsesineffective to render said one of said latter selector switches inertduring the transmission of said one of said series of impulses and forresponding to a series of impulses thereafter to render said one of saidlatter selector switches operative, an impulse relay, and a singleslow-acting release relay for maintaining the operation of saidelectromagnetic means.

6. An automatic side-switchless selector switch provided with a movablecontact adapted to be moved to a pre-determined position, impulsetransmitting means for sending series of impulses, an impulse relay forsaid switch responsive to said series of impulses, and electromagneticmeans comprising a pair of slow-acting relays and a slowsacting releaserelay in said automatic switch whereby said movable contact .is notaffected by one of said series of impulses but is affected by one ofsaid series to be moved to its pre-determined position.

7. An automatic side-switchless selector switch provided with a movablecontact, a motor magnet for said switch for controlling the movementofsaid contact, impulse trans mitting means for supplyin series ofimpulses to said selector Switch, and electromagnetic means comprising apair of slowacting relays and a slow-acting release relay associatedwith said selector switch for rendering ineffective a certain one ofsaid series of impulses whereby the said motor magnet does not move saidmovable contact from its normal position, said motor magnet howeverbeing responsive to another series of impulses to move said movablecontact.

8. A side switchless selector switch provided with a movable contact,motor means for moving said contact, impulse generating means forsupplying series of impulses to said selector switch, andelectromagnetic means comprising a pair of slowacting relays and aslow-acting release relay for absorbing one of said series of impulseswhereby said movable contact remains inert and whereby said motor meansresponds to a subsequent series of impulses to actuate said movablecontact.

9. A telephone system including a calling subscribers telephone line andan automatic side switchless selector switch, a movable contact for saidswitch, impulse sending means at said calling subscribers line fortransmitting series of impulses to said selector switch, electromagneticmeans for said selector switch responsive to one of said series ofimpulses but not operable to move said movable contact from its normalposition and other electromagnetic means for said selector switchresponsive to a series of said impulses for causing the operation ofsaid movable contact to a pre-determined position.

10. A telephone system including a calling subscribers line and anautomatic switch provided with a line relay and a motor magnet, aninterrupt-er at said calling subscribers line for transmitting series ofimpulses to said line relay, and means including a pair of slow-actingrelays for said switch operative when the first series of impulses istransmitted to said line relay by said interrupter to render said motormagnet unresponsive thereto and thus maintain said automatic switchinert and for rendering said motor magnet responsive to a subsequentseries of' impulses transmitted to said line relay to operate saidautomatic switch.

11. An automatic side switchless switch provided with a line relayadapted to be operated over the two sides of a circuit in series, astepping magnet for said switch, a device for interrupting said circuit,means including a pair of slow-acting relays and a slow-acting releaserelay in said switch whereby when said device interrupts said circuit apredetermined number of times said line relay does not operativelyaffect said stepping magnet to operate said auto matic switch, and meanswhereby when said device interrupts said line relay at a subsequent timesaid line relay actuates sa d stepping device to operate said automatlcswitch.

12. A system of the character described including an automatic switchhaving a line relay, movable contacts for. said automatic switch, amotor device for moving the said contacts of said automatic switch, animpulse transmitter for sending series of impulses to said line relay,means comprising a release relay and a pair of slow-acting relays forrendering said motor device unresponsive to one series of impulsestransmitted to said linerelay to maintain said automatic switch inert,and for rendering said motor device responsive to another series ofimpulses transmitted to said line relay to oper ate said automaticswitch.

18. An automatic switch of the character described including a linerelay, active contacts for said switch, a motor device for moving saidactive contacts, means for intermittently operating said line relay, andcontrol means including a release relay and a pair of slow-acting relaysfor said switch whereby when said line relay is operated by the firstoperation of said first means the same does not operatively affect saidmotor device to move said active contacts, and for rendering said motordevice responsive to a subsequent operation of said line relay by asubsequent operation of said first means to operatively affect saidmotor device to'move said active contacts.

14. In a telephone system, a subscribers line, a series of switchescomprising group selectors, hundreds selectors, and connectorsdirectively controllable by the subscriber on said line for connectingwith a second line, a second series of switches comprising groupselectors, thousands selectors, hundreds selectors, and connectorssimilarly controlled for connecting with a third line, automatictelephone numbers assigned to said lines all having the same number ofdigits, said hundreds selectors of said first series of switchesprovided with means for rendering one of second line, means including aplurality of serially related directively controlled automatic switchesfor setting up a connection from said second line to said first line,means including a difierent' number of similar switches for setting up aconnection from said first lineto said second line, means for operatingsaid switches according to a uniform numbering arrangement such that'said first line and said second line are both called by means of thesamenumber of digits, one of said differentnumber of similar switchesprovided with means for rendering one of said digits ineffective toprevent the move ment of said one of said different numberof similarswitches when transmitting said digits to connect said first and secondlines.

16. In a telephone system, a first line, a second line, means includinga plurality of serially related directively controlled automaticswitches for setting up a connection from any calling line to said firstline, means including a smaller number of similar switches for settingup a connection from any calling line to said second line, means foroperating said switches according to a uniform numbering arrangementsuch that said first line and said second line are both called by meansof the same number of digits, one of said smaller number of similarswitches provided with means for rendering one of said digitsinefi'ective to prevent the movement of said one of said smaller numberof switches when transmitting said digits to connect said first andsecond lines.

17. In a telephone system, a connector switch and a line accessiblethereto, another similar connector and a second line accessible thereto,means including a plurality of serially related directively controlledautomatic trunk selecting switches for setting up a connection from anycalling line to said first line by way of the first mentioned connector,means including a different number of similar switches for setting up aconnection from any calling line to said second line by way of thesecond mentioned connector, means for operating said switches accordingto a uniform numbering arrangement such that said first line and saidsecond line are both called by means of the same number of digits, oneof said difierent number ofsimilar switches provided with means forrendering one of said digits ineffective to prevent the movement of saidone of said different number of similar switches when transmitting saiddigits to connect said first and second lines.

Signed by me at Chicago, in the county of Cook and State of Illinois,this 8th day of September, 1919.

SAMUEL SUEKOFF.

